Fracture toughness–Charpy impact test–Rockwell hardness regression based model for 51CrV4 spring steel

Abstract

Charpy V-notch (CVN) impact test values are widely used in toughness specifications for spring steels, even though the fracturing energy is not directly related to the spring’s design. Both standard and non-standard methods for determining K_Ic are expensive and time consuming. In this paper, based on the results of experimental studies on spring steel grade 51CrV4, we have tried to find an expression so as to determine the fracture toughness from a computation based on the test results of the CVN and the Rockwell C hardness. This would be a much more economical and faster way to evaluate the fracture toughness of spring steels.

Keywords:

• Spring steel
• Fracture mechanics
• Fracture toughness
• Charpy impact test
• Statistics

Acknowledgements

The authors gratefully acknowledge the supply of test steels and the financial support from Štore Steel d.o.o. for this work. The authors would like to thank Dr F. Vodopivec from the Institute of Metals and Technology for helpful remarks during the investigation.